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Adult Reconstruction

THA Revision - Acetabular Component (Jumbo Cup/Augments)

Comprehensive surgical technique for revision acetabuloplasty using jumbo cups and augments for Paprosky II/IIIA defects with detailed operative steps, complications, and exam-focused clinical scenarios

Core Procedure
intermediate
By OrthoVellum Medical Education Team

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High Yield Overview

THA REVISION - ACETABULAR COMPONENT (JUMBO CUP/AUGMENTS)

Complex reconstruction for failed acetabular components | High difficulty

Critical Danger Structures

Sciatic Nerve

Location: Exits greater sciatic notch 10-20mm posterior to posterior column, travels 15mm lateral to ischial tuberosity

Protection: Identify early with finger palpation, maintain retractor on lesser trochanter, avoid combined hip flexion and retraction posteriorly, assess with intraoperative monitoring if performing extensive posterior column work

Superior Gluteal Neurovascular Bundle

Location: Exits pelvis through suprapiriform foramen 30-40mm superior to acetabular rim, between gluteus medius and minimus

Protection: Stay distal to gluteus medius insertion, limit superior dissection to 4-5cm above acetabular rim, use Charnley retractor positioned carefully if extending exposure superiorly

External Iliac Vessels

Location: Lie 10-20mm medial to pelvic brim along iliopsoas, vulnerable during medial wall perforation or screw placement into anterior column

Protection: Drill stop technique for all anterior column screws (25-30mm maximum depth), avoid medial wall protrusion, confirm screw trajectory with fluoroscopy, assess vessel position on preoperative CT

Obturator Neurovascular Bundle

Location: Travels along obturator foramen 15-25mm medial to quadrilateral plate, at risk during ischial screw placement and medial reaming

Protection: Ischial screws directed posteroinferiorly (away from foramen), limit medial reaming depth, use curved osteotomes away from quadrilateral plate

Femoral Neurovascular Bundle

Location: Lies 20-30mm inferior and medial to AIIS along iliopsoas, vulnerable during anterior approaches and anterior column screw placement

Protection: Gentle medial retraction with tagged vessels if using ilioinguinal approach, verify anterior column screw length (maximum 30mm), maintain capsule integrity when possible

Mnemonic

JUMBOJUMBO - Indications for Jumbo Cup Selection

Mnemonic

SCREWSCREW - Principles of Screw Fixation in Jumbo Cups

Primary Indications

Paprosky Type II Defects

  • Moderate bone loss with intact columns
  • Superior migration less than 2cm
  • Cavitary or contained segmental defects
  • Distorted but identifiable acetabular landmarks
  • 40-60% bone stock remaining

Paprosky Type IIIA Defects

  • Superior migration 2-3cm above obturator line
  • Loss of anterosuperior or posterosuperior rim
  • Kohler's line intact (medial wall competent)
  • Less than 50% bone stock but columns intact
  • Teardrop still identifiable

Additional Indications

  • Recurrent instability requiring larger head/cup combination
  • Failed constrained liner requiring dual mobility
  • Periprosthetic osteolysis with progressive bone loss
  • Aseptic loosening with acceptable bone deficiency
  • Metallosis with pseudotumor requiring extensive debridement

Contraindications

Absolute

  • Active infection (requires staged protocol)
  • Pelvic discontinuity (Type IIIB - requires reconstruction cage or custom implant)
  • Superior migration more than 4cm (biomechanical center too high)
  • Non-reconstructible columns requiring structural allograft
  • Medical unfitness for major revision surgery

Relative

  • Severe osteoporosis compromising screw purchase
  • Previous radiation therapy to pelvis
  • Neurologic disorders affecting compliance with protected weight-bearing
  • Severe soft tissue compromise from previous surgeries
  • Young active patient (biological reconstruction preferred when possible)

Paprosky Classification System

Type I - Intact bone stock with minor defects, standard cementless cup appropriate

Type II - Moderate bone loss

  • IIA: Superior and medial intact, cavitary defects
  • IIB: Medial wall compromised, superior migration less than 2cm
  • IIC: Moderate superior and lateral defects

Type IIIA - Severe superolateral deficiency

  • Superior migration 2-3cm
  • Ischium and teardrop intact
  • Less than 50% host bone contact achievable

Type IIIB - Severe deficiency with pelvic discontinuity

  • Superior migration more than 3cm or discontinuity
  • Kohler's line disrupted
  • Requires reconstruction cage or custom triflange

Exam Viva Scenarios

Practice these scenarios to excel in your viva examination

VIVA SCENARIOStandard

EXAMINER

"You are revising a failed acetabular component 8 years after primary THA. Preoperative radiographs show 2.5cm superior migration and loss of the anterosuperior rim, but Kohler's line appears intact. Intraoperatively after component removal, you identify a large superolateral defect with cavitary bone loss medially. Walk me through your reconstruction strategy for this Paprosky IIIA defect."

EXCEPTIONAL ANSWER
This is a Paprosky Type IIIA acetabular defect characterized by moderate superior migration (2-3cm range), segmental rim deficiency, but preserved columns and medial wall integrity. My systematic reconstruction approach involves: First, I thoroughly debride all fibrous tissue and retrieve tissue cultures. I perform sequential hemispherical reaming starting 4-6mm larger than the extracted component, aiming to expose bleeding cancellous bone and achieve 50-60% host bone contact - I may medialized to the anatomic hip center to improve contact. For the cavitary medial defect, I perform impaction bone grafting using morcellized allograft (5-10mm particle size) with sequential compaction. For the segmental superolateral rim deficiency, I apply a trabecular metal augment - typically a 40-50mm wedge or oblique augment positioned to restore rim integrity and support the cup superomedially. I fix the augment with 3-4 screws into the superior ilium, ensuring divergent trajectories for maximum purchase, then pack morcellized bone graft behind it. I then insert a jumbo cementless cup (typically 66-70mm, which is 4-6mm oversized from my final reamer) with press-fit technique, achieving primary stability through hoop stress and peripheral rim contact. I supplement with multiple screws - minimum 4-6 total - clustered in the superior dome (excellent bone quality) and into the posterior column/ischium for rotational stability. I avoid anterior column screws due to external iliac vessel proximity. Cup positioning targets 35-40 degrees inclination and 15-20 degrees anteversion, verified with intraoperative assessment. I use a dual mobility liner to minimize dislocation risk given this is a revision scenario. Finally, I perform trial reduction confirming stability through full range of motion and stress testing before final implantation.
VIVA SCENARIOStandard

EXAMINER

"Postoperative day 1 after acetabular revision with jumbo cup, the nursing staff report that the patient has a foot drop. You examine the patient and confirm complete inability to dorsiflex the ankle and numbness over the dorsum of the foot. What is the differential diagnosis, how do you assess this patient, and what is your management?"

EXCEPTIONAL ANSWER
This represents a postoperative sciatic nerve palsy, specifically involving the common peroneal division which is most vulnerable. My differential diagnosis includes: nerve traction injury from limb lengthening (most common mechanism in revision THA), direct trauma from retractors or instruments during surgery, compressive hematoma around the nerve, thermal injury if extensive electrocautery used posteriorly, or pre-existing subclinical neuropathy unmasked by surgical stress. I immediately assess the patient with detailed neurological examination - I check motor function systematically: ankle dorsiflexion (deep peroneal - tibialis anterior, EHL, EDL), ankle eversion (superficial peroneal - peroneus longus and brevis), ankle plantarflexion (tibial division - gastrocnemius, soleus), and toe flexion (FHL, FDL). I assess sensory distribution: dorsal foot and first web space (deep peroneal), lateral leg (superficial peroneal), and plantar foot (tibial division) to determine which divisions are affected. I review the operative note for limb lengthening magnitude, retractor placement, operative time, and any intraoperative concerns. I obtain immediate postoperative radiographs measuring leg length discrepancy - more than 4cm lengthening has high palsy risk. I order baseline nerve conduction studies and EMG, though these are typically delayed until 3-4 weeks post-injury for meaningful results. Regarding management, if limb lengthening is excessive (more than 4cm), I discuss with the patient the option of returning to surgery for head/liner exchange to reduce tension, though this is rarely done unless length more than 5-6cm. Conservative management includes immediate ankle-foot orthosis (AFO) to prevent equinus contracture and assist with ambulation, physical therapy focused on range of motion (prevent contracture) and strengthening of intact muscles, patient education about prognosis and expected recovery timeline, and serial neurological examinations weekly for first month then monthly. I obtain formal nerve conduction studies at 4 weeks to differentiate neuropraxia (best prognosis, recovery 6-12 weeks), axonotmesis (moderate prognosis, recovery 3-6 months), and neurotmesis (poor prognosis, no recovery). Most sciatic palsies in THA are neuropraxia or axonotmesis with eventual recovery in 60-80% of cases. If no recovery by 9-12 months, I refer to peripheral nerve surgery for consideration of nerve exploration, neurolysis, or nerve transfer procedures. I document thoroughly given medicolegal implications.
VIVA SCENARIOStandard

EXAMINER

"You are planning to revise a 68-year-old patient's acetabular component for aseptic loosening 12 years after primary THA. The preoperative CT shows Paprosky Type IIA defect with moderate cavitary loss but intact columns and rim. In your preoperative planning, what specific assessments do you make regarding bone defect management, and what are the surgical options for reconstruction? How do you decide between a jumbo cup, trabecular metal cup with augments, or other techniques?"

EXCEPTIONAL ANSWER
For this Paprosky Type IIA defect, my preoperative planning involves systematic assessment of multiple factors. First, I analyze the CT with 3D reconstruction to quantify bone loss - Type IIA defects have intact columns, preserved rim (less than 2cm superior migration), and primarily cavitary (contained) defects rather than segmental. I measure the superior migration precisely from the inter-teardrop line to the hip center, assess Kohler's line integrity (medial wall), trace both anterior and posterior columns for continuity, quantify the cavitary defect volume in mL for graft planning, and identify any small segmental defects that may coexist. I evaluate bone quality on CT - assessing cortical thickness, cancellous bone density, and areas of osteolysis. I template for cup sizing based on the contralateral normal acetabulum and plan for 4-6mm oversizing. Regarding reconstruction options for Type IIA, I consider several strategies. A standard large-diameter cementless cup (58-62mm) with impaction bone grafting of cavitary defects is appropriate if I can achieve 70-80% host bone contact with standard reaming. A jumbo cup (more than 4mm oversized) with impaction grafting is indicated if I need 4-8mm oversizing to achieve adequate peripheral rim contact but can still obtain 50-60% host bone contact. A trabecular metal cup (Tritanium, Regenerex) provides enhanced biological fixation in compromised bone, particularly useful if bone quality is poor (osteoporosis, multiple revisions). Augments with standard or jumbo cup are needed if any small segmental defects present at rim. My decision algorithm works as follows: If I can achieve more than 70% host bone contact with standard diameter cup and minimal oversizing (0-2mm), I use a standard hemispherical cup with impaction grafting for cavitary defects - this is biological reconstruction with maximum bone preservation. If I need 4-8mm oversizing to achieve 50-60% host bone contact (common in Type IIA with reaming to bleeding bone), I proceed with jumbo cup technique - press-fit through hoop stress plus multiple supplemental screws (4-6 minimum), combined with impaction grafting for cavitary defects. If bone quality is severely compromised (metabolic bone disease, osteoporotic, previous radiation), I consider trabecular metal cups which have lower threshold for biological fixation and exhibit bone ingrowth even with less than 50% contact. For the impaction grafting component, I use morcellized allograft (5-10mm particles) with autograft from the femoral head if available, sequential compaction with reverse reaming technique, and I ensure contained defect - if medial wall deficient I need to add mesh or augment to contain the graft. I always send multiple tissue cultures intraoperatively to exclude occult infection, plan for dual mobility liner given this is revision scenario, and prepare for conversion to more complex reconstruction if intraoperative assessment reveals worse deficiency than CT suggested.

THA Revision - Acetabular Component (Jumbo Cup/Augments) - Exam Summary

High-Yield Exam Summary

References

  1. Paprosky WG, Perona PG, Lawrence JM. Acetabular defect classification and surgical reconstruction in revision arthroplasty: a 6-year follow-up evaluation. J Arthroplasty. 1994;9(1):33-44. PMID: 8163974. Seminal paper establishing Paprosky classification system for acetabular bone defects based on superior migration, column integrity, and teardrop presence - essential framework for surgical planning in acetabular revision.

  2. Ballester Alfaro JJ, Sueiro Fernandez J. Trabecular metal buttress augment and the trabecular metal cup-cage construct in revision hip arthroplasty for severe acetabular bone loss and pelvic discontinuity. Hip Int. 2010;20 Suppl 7:S119-127. PMID: 20512784. Describes technique and outcomes of trabecular metal augments in severe acetabular deficiency - 94% survivorship at 5 years for Paprosky IIIA defects demonstrates effectiveness of biological fixation with porous tantalum.

  3. Sporer SM, Paprosky WG. Acetabular revision using a trabecular metal acetabular component for severe acetabular bone loss associated with a pelvic discontinuity. J Arthroplasty. 2006;21(6 Suppl 2):87-90. PMID: 16950068. Outcomes of trabecular metal cups in severe acetabular deficiency including pelvic discontinuity - emphasizes importance of supplemental screw fixation and appropriate patient selection.

  4. Gill TJ, Sledge JB, Muller ME. The management of severe acetabular bone loss using structural allograft and acetabular reinforcement devices. J Arthroplasty. 2000;15(1):1-7. PMID: 10654454. Describes reconstruction techniques for massive acetabular defects using structural allograft and reinforcement rings - establishes principles of restoring hip center and achieving biological fixation.

  5. Sembrano JN, Cheng EY. Acetabular cage survival and analysis of factors related to failure. Clin Orthop Relat Res. 2008;466(7):1657-1665. PMID: 18465182. Systematic review of acetabular reconstruction cages showing 77% survivorship at 10 years - identifies protected weight-bearing and supplemental screw fixation as critical success factors.

  6. Garbuz DS, Morsi E, Mohamed N, Gross AE. Classification and reconstruction in revision acetabular arthroplasty with bone stock deficiency. Clin Orthop Relat Res. 1996;(324):98-107. PMID: 8595781. Describes systematic approach to acetabular bone defect classification and reconstruction options based on defect type - emphasizes achieving biological fixation and reconstituting bone stock.

  7. Berry DJ, Lewallen DG, Hanssen AD, Cabanela ME. Pelvic discontinuity in revision total hip arthroplasty. J Bone Joint Surg Am. 1999;81(12):1692-1702. PMID: 10608380. Landmark paper on pelvic discontinuity management - distraction technique with supplemental plating achieves union in 82% of cases with protected weight-bearing protocol.

  8. Guyen O, Pibarot V, Vaz G, Chevillotte C, Bejui-Hugues J. Use of a dual mobility socket to manage total hip arthroplasty instability. Clin Orthop Relat Res. 2009;467(2):465-472. PMID: 18780135. Demonstrates dual mobility liners reduce dislocation rate from 15% to 3% in revision THA with high-risk features - now standard of care for acetabular revision in most centers.

  9. Regis D, Sandri A, Bonetti I, et al. A minimum of 10-year follow-up of the Burch-Schneider cage and bulk allografts for the revision of pelvic discontinuity. J Arthroplasty. 2012;27(6):1057-1063. PMID: 22226611. Long-term outcomes of reconstruction cage with bulk allograft for pelvic discontinuity - 76% survivorship at 10 years emphasizes need for protected weight-bearing and supplemental fixation.

  10. Kosashvili Y, Backstein D, Safir O, Lakstein D, Gross AE. Acetabular revision using an anti-protrusion (ilio-ischial) cage and trabecular metal acetabular component for severe acetabular bone loss associated with pelvic discontinuity. J Bone Joint Surg Br. 2009;91(7):870-875. PMID: 19567848. Cup-cage construct technique for pelvic discontinuity combining biological fixation potential of trabecular metal with structural support of cage - 93% survivorship at mean 4.6 years validates hybrid reconstruction approach.